Ch.10 Vascular Physiology Flashcards
blood reconditioning occurs
constantly
purpose of blood recoditioning
- adjust blood flow to maintain homeostasis
what are the reconditioning organs
- digestive organs
- kidneys
- skin
what is the purpose of reconditioning organs
- receive more blood then need so has the ability to redistribute it
non reconditioning organs include
- brain
- skeletal musclesw
what is the purpose of non reconditioning organs
- increase blood supple to achieve homeostasis
flow rate formula
FR=P/R
what is the pressure gradient
- the pressure difference between the beginning and end of the vessel
where does blow flow in the pressure area
- moves from an area of high concentration to low concentration
- moves down the pressure gradient
resistance is
the measure of opposition to the blood flow
increased resistance ________ flow rate
decreases
what are the three factors that influence resistance
- vessel viscosity
- vesssel lenght
- vessel radius
what is the MAJOR determinate of resistance
- vessel radius
how does vessel radius effect resistance
decreased radius = increased resistance
how does vessel lenght effect resistance
longer vessel = more surface area = increased resistance
how is vessel viscosity determined
- by the number of RBC’s
how does vessel viscosity effect resistance
increased viscosity = greater resistance
arterial blood pressure =
constant
arteries are also know as
rapid transit pathways
resistance in the arteries is
little
arteries act as
pressure reserviours
why are arteries known as pressure reservoirs
- they are the driving force for blood when the heart is relaxing
Pulse pressure formula
PP= SBP - DBP
what is normal pulse pressure
40 mm HG
what is pulse pressure
- pressure difference between systolic and diastolic pressure
systolic pressure
- maximum pressure excreted in the arteries
- when the ventricles contracts
what is normal systolic pressure
120
diastolic pressure
- minimum pressure in the arteries
- ventricles relaxes
what is normal diastolic pressure
80
Mean arterial pressure formula
MAP = DP + 1/3 SP
what is normal MAP
93
what is mean arterial pressure
- the average pressure driving blood forward into tissues throughout the cardiac system
MAP must be high enough to
ensure sufficent driving pressure
MAP must not be too high because
it will make excess work for the heart and ruture the capillaries
arterioles are
major resitance vessels
why are arterioles known as major resitance vessels
- because they vasoconstrict
arterioles makeup
- highly musclular
- contain very little elastic tissue
Purpose of arterioles
- adjust to recondition organs
- help reguate MAP
vasoconstriction
- narrowing of the vessel wall
vasoconstriction effect on resistance
- increases resistance
vasodilation
- relaxation
- enlargement of the circumfrance of the vessel
vasodialtion effect on resistance
- decreases resistance
increased myogenic activity causes
myogenic activity = ability of blood vessels to constrict
vasoconstriction
decreases oxygen causes
vasodilation
increases carbon dioxide casues
vasodialation
increased endothelin causes
vasoconstriction
decreased myogenic activity causes
vasodilation
increased oxegen casues
vasoconstriction
decreased carbon dioxide casues
vasoconstriction
decreased sypathetic stimulation causes
vasodialtion
increased heat causes
vasodilation
decreased heat causes
vasoconstriction
increased sympathetic stimulation causes
vasoconstriction
increased sympathetic stimulation is caused by
- an increase is vasopressin
- an increase in angiotension II
decreased sypathetic stimulation is caused by
- increased histamine
types of intrinsic controls
- chemical influences
- physical influences
what are intrinsic controls
- changes within a tissue / organ
- alters radius of a vessel by altering smooth muscle
What are chemical influences
- local metabolic changes
- histamine release
what are physical influences
- hot / cold
- chemical responce to shear stress
- myogenic responce to stretch
extrinsic controls are important in
blood pressure regulation
extrinsic controls examples
- neural inputs (hormones)
Capillaries are known as
“exchange vessels”
why are capillaries known as exchanged vessels
-they have maximized surface area and maximized diffusion
- slow velocity
what does slow velocity do
- allow enough time for exchange
Velocity of blood flow is _____________ to total cross sectional area
inversly proportional
Hwo are substances exchanged through cappilaries
- diffusion
- bulk flow
the lymphatic system provides
an excessory route by which fluid can be returned from the interstial fluid to the blood
oedema is also known as
the swelling of the tissues
when does oedema occur
when too much intersticial fluid accumulates
causes of oedema
- decreases concentration of plasma proteins (kidney / liver disease, loss of plasma proteins burned from the surface)
- increased permulability of cappillary wall (allergic reactions)
veins are also known as
blood reserviours
makeup of veins
- little restance
- highly densiable
- less cross sectional area (walls appear thin and collapsed)
- little smooth muscle
- little elasticity
Main determinate of MAP
- cardiac output
- total peripheral resistance
MAP formula #2
MAP = CO x TPR
sympathetic stimulation activates
a1 - adrenoceptors
Parasympathic stimulation effect on blood pressure
decreases
hypovolmic shock effect on CO
decreases
Hypovolmic shock is
low volume shock
Hypovolmic shock causes
- sever haemorrhage
- excessive vommiting
- diarrhoea
- urinary losses
cardiogenic shock is
heart produced shock
cardiogenic shock is caused by
- weekend heart
cardiogenic shock effect on cardiac output
decreased CO
vasogenic shock is
vessel produced shock
vasogenic shock effect on total peripheral resistance
decreases
vasogenic shock is caused by
- septic shock
- anaphylactic shock
effect of septic shock
vasodilator released from bacteria
effect of anaphylatic shock
- increased histamine —> vasodialtion
neurogenic shock is
nerve produced shock
neurogenic shock effect on TPR
decreases
Effect of Neurogenic shock
decreased sympathic activity —> decreased vascular tone —> vasodialtion
